Best suited for ages 16+
Table of Contents
- Periodic Table Scavenger Hunt
- Science aboard the ISS
- Cell Structure Scavenger Hunt
- Radioactive Students
- Going South for a Tan?
- Extracting DNA from Fruit!
Periodic Table Scavenger Hunt
National Research Council Canada
How much do you know about the elements of the periodic table? Use your knowledge and research skills to find the answers to these questions!
- Which element makes up the core of stars?
- Which is the lightest metal?
- Which element is known as the "king" of all elements?
- Which element makes up approximately 78% of the Earth's atmosphere?
- Which well-known plastic is made of fluorine and carbon?
- Which white metal is so soft that it can be cut with a knife?
- Which element burns in both air and nitrogen?
- Which element has the highest malleability (can be pounded into very thin sheets) and ductility (can be pulled into a thin wire)?
- Which element is an important component of haemoglobin?
Science aboard the ISS
Canadian Space Agency
The Canadian Space Agency research program aboard the International Space Station examines the behaviour of colloids in microgravity. Colloids are mixtures with properties that make them especially hard to separate. Here is an activity on the separation of mixtures. You will have to apply several separation techniques in order to identify which of three mixtures is a colloid.
Experiment Objective:
Identify the colloid among the following three mixtures: (1) vegetable juice, (2) 3.25% milk, (3) vinaigrette.
Separation Techniques - Decantation, paper filtration and centrifuging
- Decantation - This process makes use of the principle of sedimentation, i.e., the property of non-mixable liquids to form layers according to their relative densities.
- Paper filtration - Filter paper has numerous tiny holes that allow liquids to pass through while trapping solid particulates on the paper.
- Centrifuging - A rotating body tends to be projected toward the outside of the circle it describes. The components of a heterogeneous mixture subjected to rapid rotation will form layers according to their relative densities. In a sense, centrifuging is an acceleration of the sedimentation process.
Materials needed for each of the three mixtures:
A. Decantation
- 1 separating funnel
- 1 metal ring
- 1 universal holder attachment
- 2 100 ml beakers
- 50 ml - vegetable juice, 3.25% milk, vinaigrette
B. Filtration
- 1 funnel
- 1 metal ring
- 1 universal holder attachment
- 2 100 ml beakers
- 50 ml - vegetable juice, 3.25% milk, vinaigrette
C. Centrifuging
- 1 centrifuge
- 2 conical centrifuge test tubes
- 1 100 ml beaker
- 50 ml - vegetable juice, 3.25% milk, vinaigrette
A warning about centrifuging
Make sure that the conical centrifuge test tubes are placed opposite one another and filled exactly to the same level (i.e., two-thirds) to avoid unbalancing the centrifuge.
Let the centrifuge spin for about five minutes.
Allow the centrifuge to slow gradually with no external influences.
Do not try to stop it manually.
Experimental procedure
Suggest an experimental procedure to apply the three separation techniques to each mixture.
Tip: shake the vegetable juice and vinaigrette thoroughly before applying the separation techniques.
Observations
Record your observations in the table below.
(1) Vegetable juice
- Decantation:
- Filtration:
- Centrifuging:
(2) 3.25% milk
- Decantation:
- Filtration:
- Centrifuging:
(3) Vinaigrette
- Decantation:
- Filtration:
- Centrifuging:
Analyze your observations.
Analysis (1):
Analysis (2):
Analysis (3):
Form a conclusion for each hypothesis.
Conclusion (1):
Conclusion (2):
Conclusion (3)
Which of the three mixtures is a colloid?
What are the components of this mixture?
Cell Structure Scavenger Hunt
National Research Council Canada
Use your knowledge of cell structure to answer the following questions.
- This material within the nucleus contains hereditary or genetic information called genes:
- These are a stack of flattened membrane-bound sacs involved in the storage, modification, and secretion of proteins and lipids:
- This organelle is the site of aerobic respiration and ATP production:
- These organelles are the sites of protein synthesis:
- These extend from the envelope of some viruses and help the virus attach to a living organism:
- This membrane-bound, fluid-filled space in plant and animal cells stores food, water, and waste material:
- This cellulose layer surrounds the plasma membrane of plant cells:
- This is a complex system of membrane-bound channels extending throughout the cytoplasm of cells:
- This layer encloses the genetic material of a virus:
- This is a whip-like tail that helps some bacteria to move:
- This membrane surrounds the cytoplasm:
- This layer surrounds the protein coat of some viruses:
Radioactive Students
Natural Resources Canada
This activity explores exponential decay, radioactive decay processes, half-lives, and absolute dating.
While you can perform this activity with a class of any size, it works best with large groups - the bigger the better!
The Science
Isotopes are different forms of the same element where an atom has the same number of protons, but a different number of neutrons. For example, every isotope of Carbon has 6 protons, but can have anywhere from 2 to 16 neutrons! Of all these isotopes, only carbon-12 (12C, with 6 protons and 6 neutrons), carbon-13 (13C, with 6 protons and 7 neutrons) and carbon-14 (14C, with 6 protons and 8 neutrons) occur in nature, and the rest are only formed artificially in laboratories.
Some isotopes are stable: they can remain indefinitely in nature without changing. Other isotopes are unstable, and will undergo radioactive decay where the atom nucleus will emit energy and sometimes even particles until it reaches a stable state. Carbon-12 and Carbon-13 are stable, while carbon-14 is unstable, decaying into stable nitrogen-14 (14N, with 7 protons and 7 neutrons). The original radioactive isotope is the parent isotope (14C), and the isotope the parent decays into is the daughter isotope (14N).
A radioactive parent isotope has a 50% chance of decaying into its daughter product within its half-life. By measuring the ratio of parent to daughter isotopes, scientists can determine the age of a material for approximately six half-lives. Different isotopes have different half-lives, so they are useful for measuring different time frames. For example, carbon-14's half-life is approximately 5730 years, which means it can be used to date objects for approximately 34,000 years (6 x 5730 = 34,380 years), or sometimes longer with increasing error. This is why carbon-14 dating is often used to date human artefacts. By contrast, the decay of potassium-40 (40K) into argon-40 (40Ar) occurs over a half-life of 1.3 billion years, making it suitable to measure geological events since the formation of the Earth.
The Activity
Students will demonstrate the process of radioactive decay by acting out the changing ratio of isotopes present in a substance over time.
- Make a table with three columns: Half-life, Parents, Daughters. Fill out the first row as half-life = 0, parents = total number of students, daughters = 0. Add other rows for additional half-lives.
- All students start the activity seated. They represent radioactive parent isotopes.
- To represent the first half-life, every student flips a coin once. Anyone who flips a "heads" remains a parent isotope and stays in their seat. Anyone who flips a "tails" has decayed into the daughter isotope, and comes to the front of the class. Record the new count of parents and daughters in the second row of the table. If desired, assign one of the "daughters" to act as the recorder.
- Repeat for additional half-lives. For each half-life, all seated students flip their coin once. "Heads" remain parent isotopes and stay seated; "tails" become daughters and move to the front. Record the results in the table. Repeat until all students have decayed into daughters.
Variants & Extensions
- If a student arrives mid-way through the activity (or leaves during the activity), use that as an opportunity to discuss the limitations of radioactive dating with respect to closed systems.
- Randomly select some students (parents or daughters) and ask them to leave the room, skewing the table numbers. Use this as an opportunity to discuss the limitations of radioactive dating with respect to closed systems.
- Randomly pick some students to start off at the front of the room. These represent daughter-isotopes present in the initial composition, not produced by decay. Discuss how this composition would affect the accuracy when using isotopes to determine the age of material.
- Have daughters flip coins to produce decay chains of multiple radioactive reactions. An example of a decay chain is the uranium series, where uranium-234 (234U) decays into thorium-230 (230Th), a radioactive isotope which eventually decays into lead-206 (206Pb).
- Have students roll dice, where odds decay into daughters, and events remain as parents until the next half-life. Assign each odd number a different place in the room, representing different daughter isotopes that can be produced from the same parent decaying through different radioactive processes. For example, thorium-212 (212Th) can decay through emission of alpha particles into radium-208 (208Ra), or through emission of beta particles into actinium-212 (212Ac).
- Divide the class into two groups, and conduct the experiment with two different parent/daughter isotope chains with different half lives. E.g. group 1 flips a coin every minute; group 2 flips a coin every 3 minutes. Use the results to discuss cross-validating data and/or the impact of half-life duration on appropriate dating age ranges and error ranges. An example of simultaneous paired decay chains are uranium-235 (235U) decaying into lead-207 (207Pb) with a half-life of 700 million years, while uranium-238 (238U) decays into lead-206 (206Pb) with a half-life of 4.5 billion years.
- Compare the ratio of parent isotopes to daughter isotopes from your activity with the theoretical perfect 50:50 ratio expected by exponential decay. Use any variations to discuss error ranges: remind the class that although it is statistically a 50% chance of decay each half-life, the results are not precisely a 50% decay rate every time interval. This is a great way to discuss real-world error in radiometric dating with advanced students.
- For advanced students, use the data to try to derive the age equation, or use the age equation to determine the decay constant λ:
D = D0 + N (eλt - 1)
where D is the number of daughter isotopes at the current time (the tth row in the table), D0 is the original number of daughter isotopes (0), N is the number of parent isotopes at the current time (the tth row in the table), t is time (the table row), and λ is a decay constant related to the half-life. - For advanced students, plot an isochron to solve the equation graphically. An isochron is a method of visualizing the daughter and parent isotopes with respect to the normal abundance of a stable isotope of the daughter element. Then, the y-axis illustrates an increasing enrichment of the daughter isotope with respect to the background, and the x-axis represents an abundance of the parent isotope with respect to the background, eliminating the need to know the starting quantity of parent or daughter isotope. For example, rubidium-87 (87Rb) decays into strontium-87 (87Sr), and strontium-86 (86Sr) is a naturally-occurring stable isotope of strontium. An isochron of rubidium-strontium decay plots 87Sr/86Sr on the y-axis, and 87Rb/86Sr on the x-axis. In your classroom, a stable isotope of the daughter isotope may be the number of people who usually sit in the front of the class (1, if only the teacher is normally at the front of the class). It is unlikely that every student will reach the front of the classroom at the exact same time. Bring this to the students' attention and discuss that not all the parents decay into daughters at exactly the same time within the half-life. The margin of error will vary depending on when the count is taken.
Going South for a Tan?
Health Canada
The intensity of solar radiation depends partly on the latitude of a given place and time of year.
We know the sun is directly overhead at the:
- Equator (0°) on/about March 21 and September 21 (spring and autumn equinoxes);
- Tropic of Cancer (23.5°N on/about June 21 (summer solstice);
- Tropic of Capricorn (23.5°S on/about December 21 (winter solstice).
The sun therefore moves through a latitude range of 47° every six months (182.5 days) or about one degree of latitude every four days.
Knowing this, we can calculate when the sun will be directly overhead in different latitudes.
For example, the sun will be directly overhead at 10°S latitude on:
- 23.5°S - 10°S = 13.5°S
- 13.5°S x 4 days/degree = 54 days after December 21 (when the sun was overhead at 23.5°S)
- Adding 54 days to December 21, the date is February 13.
| Vacation Site | Latitude ( ° ) | Date of Overhead Sun |
| Montego Bay, Jamaica | ||
| Cancun, Mexico | ||
| Acapulco, Mexico | ||
| Rio de Janeiro, Brazil | ||
| Havana, Cuba | ||
| San Jose, Costa Rica | ||
| Ambergris Caye, Belize |
Questions
- What is the relationship between UV radiation and the angle of the sun's rays?
- At what time of year are you most susceptible to UV radiation in these places?
- What is the second time in the year when the sun's angles will be directly overhead?
- Trick question: When are the sun's rays directly overhead in your home latitude?
Extracting DNA from Fruit!
Natural Sciences and Engineering Research Council of Canada
By: Dr. Tamara Franz-Odendaal, PhD, NSERC Chair for Women in Science and Engineering (Atlantic Region)
Timing: 60 minutes
Learning Objectives
- Use proper laboratory equipment and safety rules
- Understand the importance of DNA and why scientists would want to extract it from plants and animals.
Overview
Every cell in a plant or animal contains DNA or deoxyribonucleic acid. DNA is essential to all life on earth, it carries the instructions to create new life and sustain existing life. Scientists study DNA for several reasons including; to understand how its instructions help our bodies function normally, to modify existing DNA in plants or animals to create medicine or disease resistant crops, and studying DNA can also help solve crimes! In this lab you will extract, isolate and observe DNA from fruit using common household materials!
Materials
- Piece of soft fruit such as strawberry or banana
- 1 zipper-lock bag
- Two 50 ml tubes or jars (with lid)
- 5 ml (1tsp) of clear dish soap
- ¼ teaspoon of table salt
- 80 ml of distilled or bottled water
- Coffee filter
- Elastic band
- 250 ml beaker or jar
- Chilled rubbing alcohol (about 30 ml)
- Plastic Pipette (optional)
Procedure
- Place your rubbing alcohol in the freezer to chill.
- Making your fruit mash:
- Break fruit into chunks and place into the zipper-lock bag.
- Add 60 ml of distilled water into the bag.
- Seal the bag very tight and use your hands to mash the fruit with the water.
- Making a buffer:
- Place ¼ tsp of salt into a 50 ml tube or equivalent jar with lid.
- Add 1 tsp of dish soap.
- Add 4 tsp of distilled water.
- Add 2 tsp of fruit mash.
- Seal the tube or jar and invert about 20 times. *do not shake as this causes too many bubbles to form!
- Place tube or jar in warm water for about 5 minutes.
- Filtering:
- a.Place a coffee filter over the top of a 250 ml beaker or jar and secure with a rubber band as pictured below.
- b.Retrieve your fruit buffer mixture from the warm water and pour all contents of tub or jar into the filter slowly and wait.
- Precipitating:
- Fill your other clean 50 ml tube or jar with 30 ml (6 tsp) of the chilled rubbing alcohol from the freezer.
- Add 1 pipette full or 2 tsp of filtrate liquid at the bottom of the beaker or jar into the jar with the rubbing alcohol.
- Watch the DNA precipitate out of solution; it will look like a clear, stringy substance.
Important Concepts
- Each component of the DNA extraction plays an important role. The soap helps to dissolve the cell membranes, the salt helps break up the protein chains that hold the DNA together, and the rubbing alcohol is used to precipitate out the DNA strands because DNA is not soluble in this substance.
- DNA is essential because it contains the code to build living things.
Dr. Tamara Franz-Odendaal, PhD NSERC Chair for Women in Science and Engineering (Atlantic Region) www.wiseatlantic.ca
A biologist and a previous NSERC University Faculty Awardee, Dr. Tamara Franz-Odendaal, has established a vibrant growing research group at Mount Saint Vincent University. Her research program focuses on the comparative development of the vertebrate skeleton, with particular focus on the neural crest derived craniofacial skeleton.